Process of precipitating gold from chlorid or bromid solutions.



UNITED STATES PATENT OFFICE.

FREDERICK WILLIAM MARTIN 0 AND FRED ERIO STUBBS, OF SHEFFIELD, ENGLAND.

PROCESS OF PRECiPlTATlNG GOLD FROM CHLORID OR BROMID SOLUTIONS.

SPECIFICATION forming part of Letters Patent No. 637,140, dated November14, 1899.

Application filed March 20, 1899. Serial No. 709,835. (No specimens.)

To all whom it may concern.-

Be it known that we, FREDERICK WILLIAM MARTINO and FREDERIO STUBBS,subjects of the Queen of England, residing at .Sheflield, England, haveinvented certain new and useful Improvements in-or Relating to thePrecipitation of Gold from Ohlorid or Bromid Solutions Containing It,(for which application for patent has been made in England, No. 5,034,dated March 7, 1899,) of which the following is a specification.

This invention relates to improvements in the precipitation of gold fromchlorid or bro mid solutions containing it, the solutions re ferred tobeing such as are produced in the well-known chlorination process andthe less-known permanganate and bromid processes.

Under the phrase permanganate process are included the various methodsby which gold is extracted from its ores by the use of permanganates ormanganates of potash or soda. The details of these processes form nopart of the present invention, and it is sufficient to say that thegold-containing solutions obtained by them are usually chloridsolutions.

The essential feature of this invention is the employment forprecipitating gold from the abovementioned solutions of metalliccarbids,-which when brought into contact with water produce ahydrocarbon gas, or the employment of such hydrocarbon gases howeverthey may be manufactured.

Oarbids of the metals of the alkaline earths calcium and barium carbids,for instanceproduce acetylene when treated with water, and methane isproduced in a similar manner from aluminium carbid.

In the following specification the terms metallic carbid and hydrocarbongas are to be understood as referring, respectively, to the carbide andgases above mentioned.

In carrying out this invention a hydrocarbon gas is passed through achlorid or bromid solution containing gold ora metallic carbid is addedto the liquid, thus producing a nascent hydrocarbon gas. In either casethe chlorid or bromid of gold is decomposed and the metal precipitated.

If the chlorid or bromid solution contains free chlorin or free bromin,it may be found advisable before treating the solution by the methodherein described to remove the excess of chlorin or bromin by anyconvenient process, preferably by passing a current of air through thesolution, in order to avoid the waste of metallic carbid or hydrocarbongas, which is necessary to neutralize these elements beforeprecipitation commences.

In the permanganate process the small quantity of permanganate presentin the so lution of auric chlorid is immediately decomposed by themetallic carbid or hydrocarbon gas,- and precipitation of gold thenproceeds rapidly.

Heat from any outside source may, if desired, be applied during any ofthe stages constituting this improved process.

The following are the probable chemical reactions which take placeaccording to this invention when- (a) Acetylene is passed through asolution containing chlorid of gold:

(b) Acetylene is passed through a solution containing bromid of gold:

(0) Calcium carbid is added to a solution containing chlorid of gold:

((1) Calcium carbid is added to a solution containing bromid of gold:

It is to be understood that acetylene and calcium carbid are merelygiven as convenient examples of the hydrocarbon gases and the metalliccarbids referred to in the specification.

Having now particularly described and ascertained the nature of thisinvention and in what manner the same is to be performed, we declarethat what we claim is 1. The process for the precipitation of gold fromaqueous chlorid or bromid solutions, consisting in treating suchsolutions with a hydrocarbon gas such as is produced when a metalliccarbid is decomposed by water.

2. In a process for the precipitation of gold from aqueous chlorid orbromid solutions by treating such solutions with a hydrocarbon gas suchas is produced when a metallic carbid decomposable by water isdecomposed by 10 water, the addition of a metallic carbid to the chloridor bromid solution to produce the hy'= drocarbon gas in a nascentcondition.

In witness whereof we have hereto set our hands in the presence of thetwo subscribing witnesses.

FREDERICK WILLIAM MARTINO: FREDERIO STUBBS; Witnesses:

THOMAS HARVEY, JOSEPH BRIGHT;

